The mobile type radio or wireless communication devices such as automotive telephones, portable wireless telephones or the like are coming into wide use, because they allow communication to be feasible regardless of time and place. The propagational characteristics of radio waves differ according to their frequencies, and the radio waves attenuate in their propagational energy, and decrease in their reaches as their frequencies are elevated. Therefore, the radio waves are difficult to propagate in areas or places blocked by buildings or mountains when the radio waves belong to the microwave or the millimetric wave band which is applied in the field of the mobile radio or wireless communication. Moreover, in the microwave or the millimetric wave band, the radio waves are damped in their propagational energy owing to rain, fog or mist, and this denotes that radio waves of high frequencies in the microwave or the millimetric wave band come to approach light in their properties.
In this case, the foregoing trouble in which the radio waves are difficult to propagate can easily be mitigated if the radio waves are strengthened in their propagational energy to emit them. However, this countermeasure can by no means be accepted if the radio waves cause a harmful effect on the human body. Particularly, in polyclinics which are equipped with a great number of electronic medical systems, the radio waves emitted cause the electronic medical systems to malfunction, and this is a subject of public discussion.
Therefore, it is completely out of the question to strengthen the propagational energy of the radio waves to be emitted from the mobile type radio or wireless communication devices.
In Japan, many of the mobile type radio or wireless communication devices use radio waves of 100 MHz or more in their frequencies, and for example, the automotive digital wireless telephones or the portable wireless telephones employ radio waves chiefly of 1.5 GHz rather than 800 MHz in their frequencies. Also, in a simpler portable digital wireless telephone called PHS in Japan which stand for Personal Handy Phone System, a radio wave of 1.9 GHz in the frequency thereof is applied.
The digital type radio or wireless communication is wider in the occupied band width of frequency thereof than the analogue type radio or wireless communication, and it is difficult to take many communicating channels for the digital type radio or wireless communication. However, as compared with the analogue type communication in which the communicating quality suddenly deteriorates as the radio wave under reception becomes faint, the digital type communication less deteriorates in the communicating quality to some level of field intensity of the radio wave.
Generally, in the digital type portable radio or wireless telephones for which a radio wave of 1.5 GHz in the frequency thereof is used, the communicating unit area comprises small zones of 5 km to 10 km in radius, and a base station is required to be located every three zones in their intersecting points. For example, when the digital type portable radio or wireless telephones which are operated in the district of Osaka Prefecture are brought into that of Fukui Prefecture in Japan, such telephones deteriorate in their communicating performance, and become finally incapable of their communicating operation, because these two districts are different service areas of the telephone company.
Also, the digital type portable wireless telephones can readily be affected by surrounding noises, and within manufacturing factories and automobiles in which there are a great deal of noises, it becomes frequently difficult to allow the communicating operation of the digital type portable radio or wireless telephones.
Moreover, the television uses radio waves of 30 to 3000 MHz in their frequencies for the electric signals thereof, and the automotive television deteriorates in its reception of the radio waves when, for example, it is moved along the skirts of mountains.
The present invention is submitted to improve the foregoing disadvantages of the mobile or stationary type radio or wireless communication devices which use a microwave band or a millimetric wave band.